Servo control system for filling machine weight setting

ABSTRACT

A servo system for controlling the weight of a charge of product dispensed by a filler to a package and for correcting weight variations of the product charge is provided wherein adjustment of the weight setting at the filler takes place after analyzing the weight of a relatively large number of packages, and determining that a predetermined number of packages have a weight which is below (or above) a preselected weight which weight is hereinafter referred to as the &#39;&#39;&#39;&#39;servo reference weight,&#39;&#39;&#39;&#39; in relation to a predetermined number of packages which have been weighed. Where a plurality of fillers are used the system also identifies the filler which filled the package being weighed so that the weight setting at the proper filler will be corrected when the selected relationship between the packages filled and those under (or over) the servo reference weight occurs. Where a bag making machine is also involved, the system will also maintain synchronism between the fillers and the checkweigher even though a bag fails to reach the checkweigher at the proper time from a given filler. When the number of packages under (or over) the servo reference weight reaches a selected number deemed to be excessive, then a weight correction will take place immediately regardless of the total number of packages which have been weighed. The weight analysis means will ignore a selected number of packages subsequent to a weight correction to allow a conveyor between the filler and the checkweigher to be cleared.

Muskat et a1.

Primary Examiner-George H. Miller, Jr. Attorney, Agent, or FirmRoot &OKeeffe [57] ABSTRACT A servo system for controlling the weight of acharge SERVO CONTROL SYSTEM FOR FILLING MACHINE WEIGHT SETTING [75]lnventors: Robert L. Muskat, Glenview; Robert H. Connors, Chicago; KingL.

Klopfenstein, Prospect Heights; Michael S. Stachnik, Chicago, all of 9I11.

[73] Assignee: Triangle Package Machinery Company, Chicago, Ill.

[22] Filed: May 2, 1972 [21] Appl. No.: 249,506

[52] U.S. Cl. 177/50 [51] Int. Cl G01g 19/52 [58] Field of Search..177/1, 50, 210; 141/83 [56] References Cited UNITED STATES PATENTS3,643,752 2/1972 Blodgett 177/50 X 2,688,459 9/1954 Merrill et al....177/50 3,116,801 l/l964 Bauder et al. 177/210 X 3,291,233 12/1966 Mayer177/1 X 3,648,741 3/1972 Croasdale et al. 141/83 X [451 Apr. 23, 1974 ofproduct dispensed by a filler to a package and for correcting weightvariations of the product charge is provided wherein adjustment of theweight setting at the filler takes place after analyzing the weight of arelatively large number of packages, and determining that apredetermined number of packages have a weight which is below (or above)a preselected weight which weight is hereinafter referred to as theservo reference weight, in relation to a predetermined number ofpackages which have been weighed. Where a plurality of fillers are usedthe system also identifies the filler which filled the package beingweighed so that the weight setting at the proper filler will becorrected when the selected relationship between the packages filled andthose under (or over) the servo reference weight occurs. Where a bagmaking machine is also involved, the system will al so maintainsynchronism between the fillers and the checkweigher even though a bagfails to reach the checkweigher at the proper time from a given filler.When the number of packages under (or over) the servo reference weightreaches a selected number deemed to be excessive, then a weightcorrection will take place immediately regardless of the total number ofpackages which have been weighed. The weight analysis means will ignorea selected number of packages subsequent to a weight correction to allowa conveyor between the I filler and the checkweigher to be cleared.

12 Claims, 5 Drawing Figures CONTINUOUS OUTPUT 15400, MEMORY RESET MOTORR WEIGHT PULSE COUNT lN PUT U HNDIEM X33141) PACKAGE COUNTER RES 70FILLE SETTl NG E TOOO INPUT UNDER ssavo mun-r nsrzneuc: WEIGHT COUNTERRESET O 00 INCREASE PULSE MOTOR TO FILLE SETTING PAC RAG E DETECTORPULSE our CYCLING com/even fP/KTENTED APR 2 3 1974 v SHEET 1 OF 4 FIG, I

--SERVO REF- WElGHT ALSO AVERAGE WEIGHT Fl G. 2

l L, 9.. a: 2 t Z 3 o. 3 a u. o

MIN ACCEPTABLE PKG. WElGHT sERvo REF. HEAV'ER WEIGHT PMEMTEB APR 2 3I974 SHEET 3 []F 4 FIG. 4

77\OPTIONS- SELECT ONE TO COMPENSATE FOR NUMBER O F TO I W CONVEYORSTATIONS- FlLLERS 2'3 mm E W 7 A C l 57 6! A A DEC- d 62 M E STEPPERSTEP #2 I /63 74 l PULSE h 65 '2 66 AND ma INPUT 69 l wr 7 7o 1 52MISPLACEMENTMEANS 58 DEC ENABLE AND 2 DISABLE WT, m (OPEN (CLOSE h [L wSWITCHES) SWITCHES I 7 1 AFTER I 4- DELAY) 5 NC E 7e a We |0 l5 4 a:PACKAGE if B w coum' 68 5 PULSEGEN. 55 59 g OVER WT- 5 75 Om REJECT w kUNDER fig AND WT. SERVO m 5 5 REF. WT. R v /7Z 1: 1 5 CYC L E PULSE GEN76 UNDER NC A START REJECT V O' A l6 7l/ C 7 PULSE OUTPUT K PACKAGEDETECTOR CYCLE BAG A START MACHINE PULSE OUT commuousur CYCLING CONVEYOREMEHTEUAPII 23 I974 SHEEI I [1F 4 FIG. 5

CCBUSQSQB SELECT ONE TO COMPENSATE FOR N UM BER OF CONVEYOR STATIONS ToFILLER CONTINUOUSLY CYCLE CONTROLS II II CYCLING BAG MACHINE I i 87/sTEPPER 57 STEP PULSE T\ INPUT 6? AND 58 MISPLACEMENTMEANS DISABLEENABLE k I AND ICPE N (CLOSE I swITCHEs) SWITCHES 73 AFTER ELAY) P--5675 86 AND 78 l5 w 0: PACKAGE u couNT g 5 PULSE GEN. /65 59 '1'? 67 5UNDER 9 AND M SERVO 72 5 REF. w-r. on PULSE GEN. CYCLE UNDER INT. J 76START REJECT l8 AND PULSE OUTPUT I PACKAGE 4/] DETECTOR JAI PULSE OUT LCYCLE START CYCLING CONVEYOR SERVO CONTROL SYSTEM FOR FILLING MACHINEWEIGHT SETTING BACKGROUND OF THE INVENTION It is a well recognizedproblem in the packaging industry that package filling machines eventhough set to dispense a charge of a given weight will produce packagesof varying weights. These variations are the result of the presence ofmany variables such as product density, atmospheric conditions, physicalcondition of the filler and the like. If the weights of a number ofpackages are plotted as the number of packages against the packageweight the resulting graph will resemble a probability curve.

There are critical limits in practically all packaging problems from theweight standpoint. For example, Government regulations require that theactual weight of a package must be not less that the weight printedthereon or at least a minimum weight thereunder, and thus the weight ofa package which would violate such regulation is a critical limit.Conversely, a critical weight limit could be a weight which anythingthereabove would be undesirable, harmful or even dangerous. For example,aerosol containers have critical limits of certain chemicals above whichthe product might explode, or, in other instances, the addition orpresence of certain chemicals in compounds, such as drugs, if in excessof a predetermined amount, could be harmful.

It, therefore, becomes necessary to control the weight of the package bycorrecting the weight setting at the package filler from time to time inaccordance with whether too little or too much product is beingdispensed. In some such systems a weight correction signal is originatedfor every package under or over a preselected weight range, but thisunnecessarily changes the weight setting upon the occasional occurrenceof weight deviations outside of said range, and thus the setting remainsin error until corrected by a servo signal from some subsequent package.

In other instances, systems have operated on the basis of locating theservo reference weight at the center of the probability curve. Suchsystems operate on the principle that half of the package weights mustbe less (or more) than the servo reference weight. This is undesirablebecause, when the curve broadens due to certain conditions at thefiller, an excess number of packages will be rejected as below (orabove) the critical limit or the minimum (or maximum) acceptable packageweight. Likewise, when filler conditions cause the curve to becomenarrower the average package weight is unnecessarily higher, resultingin too much give away of the product.

Again, if a weight correction occurs only at predetermined timeintervals or after each predetermined number of packages, then theinefficiency of the system could produce a large number of eitherrejects or give aways unnecessarily.

U.S. Pat. Nos. 3,620,316 and 3,643,752 are examples of problems in thisfield and of attempts which have been made to solve them.

SUMMARY OF THE INVENTION provided which is located at one or the otherside of the mean or average weight of a number of packages as determinedby the probability curve. Since the vast majority of package weightproblems is concerned with underweight (and thus a probably violation ofGovernment regulations), the description of the invention will relate,in its more specific sense, to package weights which are below the servoreference weight. It will be understood, however, that what is saidherein and described as the invention applies equally to the situationwhere it is undesirable for some reason to have weights in excess of amaximum acceptable weight and wherein the servo reference weight is setnear but below said maximum. In the former instance, the inventioncontemplates the placement of the servo reference weight at some pointbetween the average weight and the minimum acceptable package weight(critical limit). In the latter case, the invention contemplatesplacement of the servo reference weight between the average weight andthe maximum acceptable package weight.

In combination with this the invention further embodies the adjustmentof the filler weight setting only after an analysis or a study has beenmade of a relatively large number of packages. The number of packagesanalyzed is not critical and may be varied as de sired, but, in anyevent, the invention contemplates the use of computing means or logicmeans programmed to originate a weight correction signal upon theexistenc of certain predetermined conditions. I

In this connection, the total number of packages being weighed by thecheckweigher is counted, and of these packages being counted the numberof packages whose weight is below (or above) the servo reference weightis also counted, and this information is fed to computer means. Thecomputer means are programmed to detect certain preselectedrelationships between the aforesaid first and second counting means, andwhen any one of such relationships is detected a weight correctionsignal is sent to adjusting means associated with the filler weightsetting, and such weight setting is increased or decreased in accordancewith the selected relationship.

While filler weight corrections are normally made only after aconsideration of the comparative weights of a relatively large number ofpackages, nevertheless the invention provides for a weight correctionafter a relatively small number of packages have been weighed if thissmall number indicates a trend toward one weight extreme. In such casethe logic means-will not wait until the larger number of packages hasbeen weighed before a weight correction takes place.

Where multiple fillers are used to fill packages emanating from a singlesource, i.e., a bag forming, filling and sealing machine, or packages ona conveyor, the invention will identify the filler which filled apackage on the checkweigher. In the present instance a stepping means isprovided to accomplish this result, which stepping means can beassociated with either a continuously cycling checkweigher conveyor or acontinuously cycling bag making machine. If the stepping means isassociated with the conveyor, then the conveyor becomes the master andcontrols the stepping means by identifying a particular filler at eachcyclic advancement thereof. If the stepping means is associated with acontinuously cycling bag making machine then the filler is identified ateach cycle of such machine.

Another feature of the invention is the ability to ignore packages intransit from a filler to a checkweigher after the servo system has madea correction. This again prevents overcorrection and the undesirablehunting and seeking" of a weight correction. Once a 1 correction is madethe servo system will ignore packages which have been filled prior tothe weight correction until the conveyor is cleared. In the case ofmultiple fillers this also occurs, but the number of ignored packageswill'vary. As an example, if there should be l package stations on aconveyor between a filler and a checkweigher and there is but a singlefiller, then at least l5 packages will be ignored by the servo systemafter a weight correction has been made. If there are two fillers, thenthe servo system would ignore at least eight of the subsequent packagesafter a weight correction has been made and in the case of threefillers, at least five subsequent packages would be ignored.

Where the fillers are used in connection with a bag making machine itmay occur that in a given instance a bag may not be released from amachine, in which case the time reserved for that particular bag toreach the checkweigher and be weighed passes without a package havingbeen weighed. Where multiple fillers are involved the above conditioncauses the system to become out of step and identify a filler other thanthe one which filled the package then on the checkweigher. The presentinvention is also directed to the solving of this problem by preventingthe servo system from receiving or accepting any information about apredetermined number of succeeding packages placed on'the checkweigherfollowing an empty space on the conveyor. I g

In view of the foregoing the primary object of the present invention isto overcome the disadvantages and undesirable characteristics of servosystems of the prior art as discussed hereinabove and to provide animproved system which will result in the features and benefits abovementioned.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a representation ofprobability curves indicating the servo reference weight as coincidingwith the average weight of a number of packages being weighed, andrepresents an undesirable condition;

FIG. 2 illustrates probability curves resulting from the use of a servosystem embodying the present invention wherein the servo referenceweight is below the average weight and relatively near the lowercritical limit or minimum acceptable package weight, and is used hereinfor the purpose of explaining the invention;

FIG. 3 is a logic diagram of the weight analysis means or programmedcomputer. means for accomplishing certain of the features of theinvention;

FIG. 4 is a logic diagram of a checkweigher and package weight servosystem for three fillers illustrating the manner of accomplishingcertain other features of the invention and wherein a continuouslycycling conveyor means is the master; and

FIG. 5 is a logic diagram similar to FIG. 4 but illustrating the meansfor accomplishing certain of the features of the invention wherein a bagmaking machine is the master.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Before describing thephysical details of the various features of the invention as representedby the logic diagrams, some additional background and explanation ofcertain considerations should be helpful. As is well recognized when agiven number of packages are filled by filler means having inassociation therewith a predetermined weight setting all packages thusfilled with not have the same weight. As mentioned hereinabove, due tovarying conditions at the filler, including atmospheric, product densityandthe like, some of the packages will weigh more than the filler weightsetting and others will weigh less. Thus, a probability curve isdeveloped which represents a situation where the more packages beingfilled the more packages will have a weight close to the filler weightsetting. Likewise, all of the packages presumably will fall within aminimum and maximum weight range, although fewer of the packages willhave the minimum and maximum weights.

A feature of the present invention is the use'of a single servoreference weight setting. The servo reference weight will be close tothe minimum acceptable weight so that all packages, the weight of whichfall between the servo reference weight and the minimum acceptableweight, will be counted but will not be rejected by the checkweigher. Ifsuch weight is below the minimum acceptable weight, then it will be bothcounted and, at the option of the operator, may be rejected.

One problem always present in connection with requiring minimum weightsis an excessive number of rejected packages which would add to theoverall packaging costs if they have to be repackaged. Likewise, at theother end of the scale is the problem of too much give away", i.e. if asystem is operating in an area where there are few or no rejects theremay be an excessive number of packages containing more than the desiredweight, and this situation could likewise prove costly. I

It is also recognized that probability curves will vary under varyingconditions, and if the servo reference weight setting coincides with theaverage weight as determined by the probability curve as illustrated inFIG. 1, then there may be excessive give away or excessive rejects. InFIG. 1 the servo operates on the principle that 50 percent of packageweights must be less than the servo reference weight. The short termprobability curve would be free to broaden or narrow around its center,although the center would remain essentially fixed.

This condition is undesirable as illustrated in FIG. 1 where the numeral1 indicates in a solid line the supposed or expected probability curve.It will be noted here that the lower end of the curve is at the criticallimit or minimum acceptable package weight. When conditions cause thisprobability curve to narrow as illustrated by the dotted line 2 in FIG.1, then it is evident that there will be too much give away because thelower limit never reaches the minimum acceptable package weight.

Furthermore, when the curve becomes broader as illustrated by theprobability curve 3 shown in dotted lines inFlG. 1 it will be noted thatthe lower' end thereof extends beyond the minimum acceptable packageweight, and, therefore, there will be an excess of rejections.

The present invention solves this problem-by placing the servo referenceweight nearer the minimum acceptable package weight. Again it may bementioned that the same conditions prevail if the concern is overweight,in which case the servo referenceweight would be placed on the otherside of the average weight line and near the upper critical limit ormaximum acceptable weight. This condition is illustrated in FlG. 2 wherethe probability curve 4 is a solid line and is substantially as beforedescribed, and is the curve which would be expected to result from agiven number of 5 packages being weighed. The contracted curve shown indotted lines and identified by the numeral 5 will now move toward thelower weights where there will be less give away and very few packageswould be below the critical limit or the minimum acceptable packageweight. Thus the reference weight is within the acceptable packageweight range so that a tendency toward filler weight error may bedetected and servo action taken before package rejection begins. Theexpanded curve in this instance is illustrated in dotted lines by thenumeral 6 where it will be noted that at the lower limit thereof only avery few packages are likely to be below the minimum acceptable weightand, therefore, rejected.

The logic diagrams of FIGS. 3, 4 and 5 illustrate the means by which theobjects and features of the invention are accomplished. FIG. 3represents the conditions for a single filler but it will be understoodthat this same system will be used in connection with multiple tillers,as will be explained in connection with FIGS. 4 and 5.

The servo control system of the present invention embodies a firstcounter for counting all of the packages weighed and a second counterfor counting all packages under (or over) the servo reference weight. Byway of example, only and without any limitation as to the intendedweights involved, if it is supposed that the desired weight and weightstamped on the package is 16 ounces andthef'll'er' weight setting isplaced at 16 ounces, then the servo reference weight would be set atsomething in excess of 16 ounces but less than the small range allowableunder 16 ounces without being;

rejected. For example, 15.95 ounces. Thus, an under servo referenceweight signal will be originated at the checkweigher for every package,under 16% ounces regardless of whether it is under or over the desired16 ounces, and such package will be counted by the second counting meansas well as the first counting means. If a package is in excess of the16% ounces it will be counted by the first counting means but not by thesecond counting means.

Referring now more particularly to FIG. 3, the programmed'computer meansor logic means for originating the weight correction signals to a motorat the filler which will decrease or increase the tiller weight settingis illustrated within the area identified by the dot-dash lines 7.Within this area the first package counter is illustrated generally bythe numeral 8 and the second package counter is illustrated generally bythe numeral The checkweigher is indicated generally by the numetal 10,the package detector by the numeral 11 and g The checkweigher is alsoprovided with the overweight reject 15 (with which we are not hereconcerned) as well as the underweight reject 16, and the under servoreference weight pulse generator 17.

Also associated with the checkweigher in this logicsystem is OR gate 18which receives pulses generated by the under servo reference weightpulse generator 17 and the underweight reject 16. This function isillustrated by the lines 19 and 20 respectively.

Associated with the OR gate 18 is an AND gate 21 which receives signalsfrom the OR gate 18 and conveys them to the count input 22 of the secondor under servo reference weight counter 9. The logic line 23 indicatesthat the AND gate 21 will receive output signals from the under servoreference weight pulse generator 17 whether or not an additional pulseis generated by the fact that a package has been rejected.

The package counter 8 is set and the computer programmed to cause theoccurrence of certain happenings when certain predetermined total countshave been recorded which have a predetermined relationship with thecounts in the second counter 9. It is to be understood throughout thisdescription that the specific numbers mentioned are intended to be forillustrative purposes only and are not intended in any way to belimitations. For example, the package counter 8 is set to count up to 99and then resets to 00. This has been selected as a desirable number, butit will be evident that any other numbers above or below this selectednumber could be used without in any way departing from the spirit of theinvention. Thus the counter 8 will register a count from 00 to 99 asindicated by the box 24.

Between the package counter 8 and the second counter 9 there isconnected a continuous output means 25 which, during normal operation ofthe system, continuously provides an enable signal to the AND gate 21.Thus, during operation of the continuous output, whenevera signal isgenerated by a pulse generator 17 indicating an under servo referenceweight package this signal will be received by the count input 22 in thesecond counter 9. There will be a count range, however, during which thecontinuous output means will be inoperative, and during the period ofthis count range no signals from the pulse generators 17 can be receivedby the second counter 9 because the AND gate 21 requires also a signalfrom the continuous output.

The purpose of this is to allow the conveyor to be cleared after aweight correction has been made as discussed hereinabove. Here again,however, the distance between a filler and a checkweigher will vary, andthe number of package stations on a conveyor between these two pointswill vary widely depending upon the customers setup in his plant as wellas the type andthe quantity of product being dispensed by the filler.The arbitrary number 15 has been selected here purely for illustrativepurposes and is not intended in any way to be limiting. Thus, inaccordance with the invention, as

illustrated by the logic diagram, the first package,

a resumption of the operation of the continuous output means 25. This isillustrated diagrammatically in the logic diagram wherein the count of15 is shown at 26 and a pulse output indicated at 27 to the on setting28 will recommence the continuous output.

In the first package counter 8 there is a second higher predeterminednumber which will cause the counter to be reset to if that number isreached and no under servo reference weight packages have been counted,i.e., the second counter 9 remains at 00 count. The reason for this isthat when a relatively large number of packages have been weighed andnone of them are under the servo reference weight this is an indicationthat there may be too much give away of product and the weight settingat the filler should be decreased. The number which has been selectedherein for illustrative purposes is 60, but again it is to be understoodthat this is purely arbitrary and any other suitable number could beselected.

In the logic diagram of FIG. 3 the counter 8 is shown as havingregistered 60 packages in the box indicated by the numeral 29. When thecounter 8 reaches this number a pulse output to the AND gate 30 willoccur through the line 31. At this time if the second counter 9registers 00 as indicated at 32 then there is a second output throughline 33 to the AND gate 30 which is carried through the OR gate 34 tothe reset device 35 in the first counter 8, thereupon resetting thecounter 8 to 00. Again the first l packages will be ignored by thecounter 9 and will not record any of said packages having a weight lessthan the servo reference weight.

If there have been one or more packages under the servo reference weightcounted by the second counter 9, then the count of 60 is meaningless andthe count will continue to 00 in the absence of the occurrence ofcertain emergency measures which will be discussed in greater detailhereinafter. If the number of packages counted reaches 00 and there havebeen very few packages which' are under the servo reference weight, itis desirable at that point to decrease the weight setting at the fillerbecause there may be too much give away. The number selected toillustrate this point as shown at 36 in the second counter 9 is thenumber 4. In other words, if the total count reaches 00 and there havebeen less than four packages under the servo reference. weight, then asignal will be carried through line 37 to -the AND gate 38. Since thisAND gate requires another signal before the decrease weight pulsegenerator 39 can function, nothing will happen except at the count of00. This may be illustrated by the lines 40 and 41 which are shown asconnecting the 00 count box to the AND gate 38. Thus, when the totalcount reaches 00 and the second counter 9 has recorded less than four(0, 1, 2 or 3) the pulse generator 39 will put out a pulse to the fillerweight setting motor which will then be acmated to decrease the weightsetting.

It has likewise been determined arbitrarily that if some number inexcess of three but below another predetermined number is the count ofpackages under the servo reference weight when the first counter reaches00, then this condition is satisfactory, and no adjustment of the weightsetting will be made. This number has arbitrarily been determined forillustrative purposes only as being 4, 5, 6 or 7. It will be noted inthe logic diagram of FIG. 3 that, in the second counter 9 there is noconnection from the box 42 containing the indication of packages 4-7, toeither of the weight pulse generators.

It has further been determined that when the total count reaches 00 andthere have been in excess of a predetermined number of packages belowthe servo reference weight the weight adjustment 'at the tiller shouldbe decreased. For this purpose the arbitrary numbers of 8, 9, 10 and 11have been selected, and again these numbers are not critical. Thus, fromviewing FIG. 3 the box 43 indicating a number equal to or greater thaneight is connected by the line 44 to the AND gate 45 indicating thatwhen the package count of the second counter 9 reaches a number equal toor more than eight a signal is put out to the AND gate 45. However, fora signal to reach the increase weight pulse generator 46 the AND gate 45must also receive another signal, and in this instance the signal willalso be through the lines 40, 41 and 47 from the first package counterwhen the count reaches 00. Thus, when the count reaches 00 and thenumber of packages under the servo reference weight has reached any oneof the numbers 8, 9, 10 or 11 a pulse will be generated to the fillerweight setting motor for increasing the filler weight setting.

A fifth condition may also exist which is undesirable, and which shouldbe corrected. That is the condition where the number of packages underthe servo reference weight is so great, compared with the total numberof packages then weighed, that there is an indication of a trend that anextreme number of packages will be under such weight. In this instancean immediate correction will be made regardless of the total number ofpackages counted.

Again, the number which has been selected to illustrate this point ispurely arbitrary, and is the number 12, as shown in the box 48 in thesecond counter 9. As shown by the connecting line 49, when the number ofunder servo reference weight packages reaches 12 an output signal to theOR gate 34 will be transmitted to the reset means 35 to causeimmediately the first package counter 8 to be reset to 00. It will benoted from the logic diagram that this will occur at any time the number12 is reached without regard to the number of packages which have beencounted by the first counter 8. Thus the counter 8 is at O0 and a signalis in lines 41 and 47 to AND gate 45; the counter 9 is at 12, and, beingin excess of 8 a signal is also present in line 44 to the AND gate 45.Hence a signal will reach the increase weight pulse generator 46.

It should also be mentioned here that after the count reaches thearbitrary number 15, not only will the continuous output signals beginto permit counting of the under servo reference weight packages, butalso, through the line 50, a signal will be transmitted to the resetmeans 51 of the second counter 9 and reset this counter back to 00.

It will be noted that the cycling conveyor, which can be eithercontinuous or intermittent, will create a pulse output for each cyclicadvancement thereof to the package detector 11. When the packagedetector sees a package on the checkweigher it puts out a signal tostart the checkweigher cycle. After the packages are filled each onewill be counted by the first counter as it reaches the checkweigher, butno packages under the servo reference weight will be counted by thesecond counter until after the total count reaches 15. However, if theweight of the package is below the critical limit or the minimumacceptable package weight, then it will be rejected at the operatorsoption regardless of the total count.

It will thus be evident from the foregoing description of the logicdiagram of FIG. 3 that we have provided novel servo control means whichis highly efficient to provide both a minimum number of rejects and aminimum amount of give away.

Logic diagrams 4 and illustrate the use of the system of FIG. 3 inconnection with a plurality of fillers. Referring especially to FIG. 4,three fillers have been indicated as operating in connection with a bagforming, filling and sealing machine. In FIG. 3 the programmed computermeans have been indicated as those means within the dot-dash line 7. InFIG. 4 there are three fillers, and, therefore three of such computermeans are indicated as being within the areas bounded by the threedot-dash lines 7.

The three computer means associated with the three fillers are indicatedas A, B and C in FIG. 4. Although the fillers are not shown, they areidentified as Nos. 1, 2 and 3. Filler No. 1 is associated with computermeans A. Filler No. 2 is associated with computer means B, and fillerNo. 3 is associated with computer means C. In this instance, acontinuously cycling conveyor 12a is the master and controls theoperation of the bag machine, the fillers, the checkweigher, and theoperation of an identification means. As indicated above, when a packagereaches the checkweigher which is under the servo reference weight it isimportant that the tiller which filled that package be identified.Therefore, we have provided as one of the features of this invention theprovision of such identification means.

In FIG. 4 there is the same package detector 11 as heretofore described,together with the checkweigher and its associated elements as shown. Inaddition thereto, a stepper device 52 is provided which is actuated bythe pulse output at each cyclic advancement of the conveyor to advancethe stepper and identify the corresponding filler.

Cycling of the conveyor originates a pulse output, at each cyclicadvancement thereof, to the package detector 11, to the cycle start ofthe bag machine 53, and to the stepper 52. This is true whether theconveyor is moving continuously or intermittently, it being understoodthat the term cyclic advancement is intended to mean each time themovement of the conveyor advances a package to the checkweigher, or atleast advances through that time period whether or not a package ispresent.

Cyclic advancement of the conveyor then starts the bag machine cycle andenergizes the pulse output of the package detector to start the cycle ofthe checkweigher. Simultaneously the conveyor output pulse will advancethe stepper 52 when the pulse reaches the step pulse input thereofthrough line 54.

The package count pulse generator, as before, will originate a countpulse, but this time it is carried through lines 55 and 56 to all of theAND gates 57, 58 and 59.

If it is assumed that the cyclic advancement of the conveyor has causedthe stepper 52 to move the switch 60 thereof to contact 61 as shown inFIG. 4, then the stepper' will be electrically connected through lines62 and 63, through line 64 to the other side of AND gate 57, thereuponactuating the count input '14 of the package counter 8 associated withthe filler means No. 1

There being no connections between the stepper and either of the otherAND gates 58 or 59, the count input of the counters associated therewithwill not be actuated.

At the next cyclic advancement of the conveyor the switch arm 60 will beadvanced to contact 65 connected through lines 66, 67 and 68 to the'ANDgate 58 of the second computer means B, associated with filler No. 2. Atthe next count pulse, generated when a package is detected on thecheckweigher, a signal output.

will again be transmitted through lines 55 and 56, but this time it willactuate the package counter in the second computer means B by goingthrough the AND gate 58 and will not reach the corresponding countersassociated with either of the other computer means A or C because theirAND gates are not connected to the stepper at that time.

The next cyclic advancement of the conveyor will move the switch arm 60to the contact 69 connected through lines 70, 71 and 72 to the AND gate59 associated with the third computer means C. The detection of anotherpackage will again generate an output signal through lines 55 and 56,but this time to AND gate 59 which is already receiving the signal fromthe stepper.

Thus, at each cyclic advancement of the conveyor the bag machine forms abag, a previously filled package will be detected and checkweighed, thefiller will be identified which filled the package then being weighed,and a filler will be operated.

In addition to the foregoing, when a package is present on thecheckweigher that is under the servo reference weight a pluse will begenerated, as before, to the OR gate 18. If the underweight issufficient for a rejection it will be rejected and a pulse will begenerated through line 20 to the OR gate 18. With the multiple fillers,however, the OR gate 18 will permit signals from the under servoreference weight pulse generator to be carried through line 73 to theAND gates 74, 75 and 76. As before, the stepper will be connectedthrough the same lines to the respective AND gates 74, 75 and 76 sothat, when a package is detected which is under the servo referenceweight, the tiller identification means will identify the filler whichfilled the package on the checkweigher. This under servo referenceweight package will be counted in the second counter 9 associated withthe respective computer means, and when any one of the predeterminedrelationships between the first and second counter exists in any givencomputer means, all as previously explained, a weight correction signalwill be transmitted to the corresponding filler weight setting motor toeither increase or decrease the weight of the subsequent charges.

The phase in which the fillers will sequentially operate will dependupon the number of conveyor stations. With three fillers there are threealternatives for connecting each filler with a particular contact in thestepper. FIG. 4 shows numerically, in vertical columns, various optionswhich can be utilized and selected, depending upon the number ofconveyor stations. This group of vertical columns of numbers isindicated generally by the numeral 77.

In an ideal operation the fillers do not miss any cycles, and bags aredeposited from the bag machine into the continuously cycling conveyor inconsecutive sequence, i.e., a, b, c, a, b, c from fillers Nos. 1, 2 and3 respectively. Many form, fill and seal packaging machines have theproperty that the first formed bag is not released from the bag machineuntil a second bag is formed. The present invention can be set up tooperate with this type of machine by properly connecting the steppercontacts with the appropriate filler.

It may happen, however, that a filler will fail to dispense a charge,the bag machine will neither form nor release a bag and thus bags willnot be deposited on the conveyor in consecutive sequence. As an example,consider the situation where filler No. 2 missed a cycle. In that casebag a filled by filler No. 1 would not be released from the bag machineuntil bag c was formed. The bags would then be deposited on the conveyorin the sequence none, a c. in this situation bag a now occupies aconveyor space normally reserved for bag b, and the conveyor spacereserved for bag a contains no bag.

To insure continued synchronization between the filler and therespective filled bags or packages formed by the bag machine, theinvention provides that the servo system will not accept any informationabout the package following an empty conveyor space, although this andall following packages will still be accepted or rejected on a weightbasis by the checkweigher.

The numeral 78 indicates generally a misplacement means whereby toassure continued synchronization and proper relationship between thepackage on the checkweigher and the filler which filled that package. Todo this there is provided in the respective lines 63, 67 and 71 from thestepper 52 normally closed switches as indicated at 79, 80 and 81,respectively. As long as these switches are closed the stepper signalswill be transmitted to the respective AND gates 57, 58 and 59. When apackage is missed, however, these switches will open, whereupon theservo system will not accept information with respect either to theempty space or to the package following the empty space.

This is accomplished by use of the invert means 82 and the AND gate 83.

During normal operation, the pulse from the conveyor is received at oneinput of AND gate 83, while simultaneously the pulse from the packagedetector 11 is received both at the checkweigher cycle start and theinvert means input. A signal present at the input of the invert means 82will cause no signal to be present at the output of the invert means,thus a second signal is not present atthe second input of AND gate 83.Hence, AND gate 83 does not place a signal into the disable input 84 ofmisplacement means 78, and switches 79, 80, 81 remain closed.

in the absence of a package, however, the package detector 11 does notgenerate an output signal to either the checkweigher cycle start or tothe invert input. Thus, the invert output does generate a signal, andthis signal, combined with the pulse out signal from the conveyor,actuate AND gate 83, which, in turn, places a signal into the input ofthe disable means 84 of the is the master. Otherwise all operations asdescribed above remain the same. in this case, however, the bag machineis indicated as 53a and is continuously cycling. The bag machine cyclecontrols the operation of the conveyor, the fillers, the checkweigherand the identification means.

Each cycle of the bag machine 53a puts out a signal to the stepper 52through line 87 to advance the switch arm 60 to the next contact. Therewill also be a pulse output from the bag machine to start the cycle ofthe conveyor 12a, and the operation from this point on is the same asthat described obove, namely, the output pulse from the conveyor enablesthe package detector to put out a pulse if there is a package presentand will start the checkweigher cycle. If there is no package, then thesignal from the output of the invert means will combine, within AND gate83, with the pulse-out signal from the conveyor 12a, and the outputsignal of AND gate 83 will cause the misplacement means to open theswitches, and the servo system will not accept information about thepackage following the empty conveyor space.

From the foregoing description it will be evident that we have providedimproved novel means whereby to achieve the objects as aforesaid and toovercome the undesirable characteristics and shortcomings of heretoforeknown servo control systems for filling machine weight settings.

Changes may be made in the form, construction and arrangement of partsfrom those disclosed herein with- I out in any way departing from thespirit of the invention or sacrificing any of the attendant advantagesthereof, provided, however, that such changes fall within the scope ofthe claims appended hereto.

We claim:

1. A servo control system for a package filling machine weight setting,wherein a series of packages being filled and weighed will have anaverage weight as well as upper and lower extreme weights, comprising:

a. a filler for dispensing a charge of product to fill a package inaccordance with a predetermined weight setting,

b. adjusting means for adjusting said weight setting,

c. checkweighing means for weighing the packages after they are filled,

d. analysis means associated with said checkweighing 4 f. weightcorrection feedback means operable in response to the detection ofcertain ones of said relationships to originate a package weightcorrection signal and actuate said adjusting means.

2. A servo control system as defined in claim 1, including further,means to originate a package weight correction signal immediately uponsaid second counting means reaching a predetermined count regardless ofsaid relationship.

3. A servo control system as defined in claim 1, in-

cluding further, means to interrupt the functioning. of

said second counting means during. the counting of a predeterminednumber of packages by said first counting means after a weightcorrection signal has been originated.

4. A servo control system for a package filling machine weight settingcomprising:

a. a filler for dispensing a charge of product to fill a package inaccordance with a predetermined weigh-t setting,

b. adjusting means for-adjusting said weight setting,

c. checkweighing means for weighing the packages after they are filled,d. analysis means associated with said checkweighing means having aservo reference weight setting between the average weight of a series ofpackages being checkweighed and the lowest weight of a package in'saidseries, and including l. afir st counting means to count all of thepack-- ages being weighed by said checkweighing means, and

2. a second counting means to count the numberof packages weighed bysaidcheckweighing. means which are below said servo reference weightsetting,

e. computer means programmed to detect certain predeterminedrelationships between the package counts in said first and secondcounting means, and

cluding further, means to originate a package weight correction signalimmediately upon said second counting means reaching a predeterminedcount regardless of said relationship.

A servo control system as defined in claim 4, in-

cluding further, means to interrupt the functioning of said secondcounting means during the counting of a predetermined number of packagesby said first counting means after a weight correction signal has beenoriginated.

A servo control system for a package filling machine weight settingcomprising:

a filler for dispensing a charge of product to fill a package inaccordance with a predetermined weight setting,

adjusting means for adjusting said weight setting,

. checkweighing means for the packages, conveying means for conveyingfilled packages to said checkweighing means from said filler,

weight correction feedback means associated with said checkweighingmeans operable to originate a package weight correction signal andactuate said adjusting means, and

. means operable after actuation of said adjusting means forinterrupting the functioning of said feedback means for a predeterminedinterval sufficient to allow said conveying means to convey to saidcheckweighing means at least a portion of all packages filled prior toactuation of said adjusting means. 8. A servo control system for apackage filling machine weight setting, comprising:

a. a filler for dispensing a charge of product to fill a package inaccordance with a predetermined weight setting,

b. adjusting means for adjusting said weight setting,

c. checkweighing means for the packages having associated therewith aservo reference weight setting,

d. a first counting means to count all of the packages being weighed bysaid checkweighing means,

e. a second counting means to count the number of packages weighed bysaid checkweighing means which are under said servo reference weightsetting,

f. first logic means operable to originate a weight correction signalbased upon the count then present in said second counting means whensaid first counting means reaches the higher one of two predeterminednumber of packages,

g. second logic means operable to originate a weight correctio signalwhen l. said f rst couiiting means reaches the lower one of twopredetermined numbers of packages and 2. saidseeaiia'cbunan meansregisters a number less than a first predetermined number, and

h. third logic means operable immediately to originate a weightcorrection signal when said second counting means reaches a secondpredetermined number regardless of the number registered by said firstcounting means. j i

9. A servo control system as defined in claim 8, in-

cluding a fourth logic means operable to interrupt the functioning ofsaid second counting means for a predetermined number of packagescounted by said first counting means after a weight correction signalhas been originated. v

10. A servo control system for a package filling machine weight settingcomprising:

a. a filler for dispensing a charge of product to fill a package inaccordance with a predetermined weight setting,

b. adjusting means for adjusting said weight setting,

c. checkweighing means for the packages having associated therewith aservo reference weight setting,

d. a first counting means to count all of the packages being weighed bysaid checkweighing means,

e. a second counting means for counting the number of packages weighedby said checkweighing means which are under the servo reference weightsetting,

f. a first logic means operable to originate a weight correction signalto actuate said adjusting means to decrease said weight setting when Vlf said first counting means reaches a predetermined count and 2. thecount present in said second counting, means is below a firstpredetermined number of packages, and I g. a second logic means operableto originate a weight correction signal to actuate said adjusting meansto increase said weight setting when 1. said first counting meansreaches the same pre-- determined count, and

2 the count present in said second counting means is above a secondpredetermined number of packages. 11. A servo control system as definedin claim 10, in-

cluding a third logic means operable to originate a weight correctionsignal to actuate-said adjusting ages counted by said firstcounting-means.

it m 1 1 "m

1. A servo control system for a package filling machine weight setting,wherein a series of packages being filled and weighed will have anaverage weight as well as upper and lower extreme weights, comprising:a. a filler for dispensing a charge of product to fill a package inaccordance with a predetermined weight setting, b. adjusting means foradjusting said weight setting, c. checkweighing means for weighing thepackages after they are filled, d. analysis means associated with saidcheckweighing means having a servo reference weight setting between theaverage weight of the series of packages being weighed and one of theextreme weights of said series, and including,
 1. a first counting meansto count all of the packages being weighed by said weighing means, and2. a second counting means to count the number of packages weighed bysaid checkweighing means which are between the servo reference weightsetting and one of its associated extreme weights, e. computer meansprogrammed to detect certain predetermined relationships between thepackage counts in said first and second counting means, and f. weightcorrection feedback means operable in response to the detection ofcertain ones of said relationships to originate a package weightcorrection signal and actuate said adjusting means.
 2. a second countingmeans to count the number of packages weighed by said checkweighingmeans which are between the servo reference weight setting and one ofits associated extreme weights, e. computer means programmed to detectcertain predetermined relationships between the package counts in saidfirst and second counting means, and f. weight correction feedback meansoperable in response to the detection of certain ones of saidrelationships to originate a package weight correction signal andactuate said adjusting means.
 2. A servo control system as defined inclaim 1, including further, means to originate a package weightcorrection signal immediately upon said second counting means reaching apredetermined count regardless of said relationship.
 2. the countpresent in said second counting means is above a second predeterminednumber of packages.
 2. the count present in said second counting meansis below a first predetermined number of packages, and g. a second logicmeans operable to originate a weight correction signal to actuate saidadjusting means to increase said weight setting when
 2. said secondcounting means registers a number less than a first predeterminednumber, and h. third logic means operable immediately to originate aweight correction signal when said second counting means reaches asecond predetermined number regardless of the number registered by saidfirst counting means.
 2. a second counting means to count the number ofpackages weighed by said checkweighing means which are below said servoreference weight setting, e. computer means programmed to detect certainpredetermined relationships between the package counts in said first andsecond counting means, and f. weight correction feedback means operablein response to the detection of certain ones of said relationships tooriginate a package weight correction signal and actuate said adjustingmeans.
 3. A servo control system as defined in claim 1, includingfurther, means to interrupt the functioning of said second countingmeans during the counting of a predetermined number of packages by saidfirst counting means after a weight correction signal has beenoriginated.
 4. A servo control system for a package filling machineweight setting comprising: a. a filler for dispensing a charge ofproduct to fill a package in accordance with a predetermined weightsetting, b. adjusting means for adjusting said weight setting, c.checkweighing mEans for weighing the packages after they are filled, d.analysis means associated with said checkweighing means having a servoreference weight setting between the average weight of a series ofpackages being checkweighed and the lowest weight of a package in saidseries, and including
 5. A servo control system as defined in claim 4,including further, means to originate a package weight correction signalimmediately upon said second counting means reaching a predeterminedcount regardless of said relationship.
 6. A servo control system asdefined in claim 4, including further, means to interrupt thefunctioning of said second counting means during the counting of apredetermined number of packages by said first counting means after aweight correction signal has been originated.
 7. A servo control systemfor a package filling machine weight setting comprising: a. a filler fordispensing a charge of product to fill a package in accordance with apredetermined weight setting, b. adjusting means for adjusting saidweight setting, c. checkweighing means for the packages, d. conveyingmeans for conveying filled packages to said checkweighing means fromsaid filler, e. weight correction feedback means associated with saidcheckweighing means operable to originate a package weight correctionsignal and actuate said adjusting means, and f. means operable afteractuation of said adjusting means for interrupting the functioning ofsaid feedback means for a predetermined interval sufficient to allowsaid conveying means to convey to said checkweighing means at least aportion of all packages filled prior to actuation of said adjustingmeans.
 8. A servo control system for a package filling machine weightsetting, comprising: a. a filler for dispensing a charge of product tofill a package in accordance with a predetermined weight setting, b.adjusting means for adjusting said weight setting, c. checkweighingmeans for the packages having associated therewith a servo referenceweight setting, d. a first counting means to count all of the packagesbeing weighed by said checkweighing means, e. a second counting means tocount the number of packages weighed by said checkweighing means whichare under said servo reference weight setting, f. first logic meansoperable to originate a weight correction signal based upon the countthen present in said second counting means when said first countingmeans reaches the higher one of two predetermined number of packages, g.second logic means operable to originate a weight correction signal when9. A servo control system as defined in claim 8, including a fourthlogic means operable to interrupt the functioning of said secondcounting means for a predetermined number of packages counted by saidfirst counting means after a weight correction signal has beenoriginated.
 10. A servo control system for a package filling machineweight setting comPrising: a. a filler for dispensing a charge ofproduct to fill a package in accordance with a predetermined weightsetting, b. adjusting means for adjusting said weight setting, c.checkweighing means for the packages having associated therewith a servoreference weight setting, d. a first counting means to count all of thepackages being weighed by said checkweighing means, e. a second countingmeans for counting the number of packages weighed by said checkweighingmeans which are under the servo reference weight setting, f. a firstlogic means operable to originate a weight correction signal to actuatesaid adjusting means to decrease said weight setting when
 11. A servocontrol system as defined in claim 10, including a third logic meansoperable to originate a weight correction signal to actuate saidadjusting means to decrease said weight setting when said first countingmeans reaches a second predetermined count, and when the count presentin said second counting means is below a third predetermined number ofpackages.
 12. A servo control system as defined in claim 10, including afurther logic means to originate a weight correction signal to actuatesaid adjusting means to increase said weight setting immediately whensaid second counting means exceeds a further predetermined number ofpackages regardless of the number of packages counted by said firstcounting means.